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Proximate And Landscape Factors Influence Grassland Bird Distributions, Mary Ann Cunningham, Douglas H. Johnson
Proximate And Landscape Factors Influence Grassland Bird Distributions, Mary Ann Cunningham, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and landscape scales on grassland birds, a group of birds of high conservation concern, in the Sheyenne National Grassland in North Dakota, USA. The Grassland contains a diverse array of grassland and woodland habitats. We surveyed breeding birds on 2015 100 m long transect segments during 2002 and 2003. We modeled …
Effects Of Distance From Cattle Water Developments On Grassland Birds, Andrea L. Fontaine, Patricia L. Kennedy, Douglas H. Johnson
Effects Of Distance From Cattle Water Developments On Grassland Birds, Andrea L. Fontaine, Patricia L. Kennedy, Douglas H. Johnson
USGS Northern Prairie Wildlife Research Center
Many North American grassland bird populations appear to be declining, which may be due to changes in grazing regimes on their breeding areas. Establishment of water developments and confining cattle (Bos taurus L.) to small pastures often minimizes spatial heterogeneity of cattle forage consumption, which may lead to uniformity in vegetative structure. This increased uniformity may provide suitable habitat for some bird species but not others. We assessed how cattle use, vegetative structure, and bird population densities varied with increasing distance from water developments (0-800 m) on the Little Missouri National Grassland (LMNG) in North Dakota. Lark buntings ( …
Assemblages Of Breeding Birds As Indicators Of Grassland Condition, Sharon Freshman Browder, Douglas H. Johnson, I. J. Ball
Assemblages Of Breeding Birds As Indicators Of Grassland Condition, Sharon Freshman Browder, Douglas H. Johnson, I. J. Ball
USGS Northern Prairie Wildlife Research Center
We developed a measure of biological integrity for grasslands (GI) based on the most influential habitat types in the Prairie Pothole Region of North Dakota. GI is based on proportions of habitat types and the relationships of these habitat types to breeding birds. Habitat types were identified by digital aerial photography, verified on the ground, and quantified using GIS. We then developed an index to GI based on the presence or abundance of breeding bird species. Species abundance data were obtained from 3 min roadside point counts at 889 points in 44, 4050 ha study plots over a 2-year period. …